The invention relates to a diagnostic radiology installation, comprising a patient support, a radiation measuring arrangement comprised of a radiation source, which generates at one least fan-shaped radiation beam penetrating the radiography subject, and disposed transversely to the patient support, and comprised of a radiation receiver which is formed by an array of detectors which are connected to a signal processing circuit, and means for effecting a relative movement between the patient support and the radiation measuring arrangement in the longitudinal direction of the support for generation of a shadow image from the detector output signals by means of the signal processing circuit.
A diagnostic radiology installation of this type is described in the German O.S. No. 26 13 809 (U.S. Pat. No. 4,174,481). The known diagnostic radiology installation relates to a computer tomograph which is supplemented with means which permit the preparation of a shadow image of a specific region of a patient. For the preparation of the computer tomogram, the measuring arrangement is rotated about the longitudinal axis of the support or about an axis which is parallel thereto. From the output signals of the detectors, a computer calculates the attenuation values of image points arranged in a matrix, which can then be reproduced as an image of the examined transverse layer of the patient. For the generation of a shadow image, the measuring arrangement is locked against rotation and a relative movement between the patient support and the measuring arrangement in the longitudinal direction of the support takes place. A shadow image thus contains, in superimposed form, all details of the irradiated radiography region. Since these details are superimposed on one another, (for example, in the case of observation of the chest, a superposition of the front and rear rib sections takes place), the image is of little significance in terms of information-content.
In order to improve x-ray shadow images, it is already known to form a sharp image of only one layer of the patient, parallel to the patient support, by fixedly coupling with one another the x-ray tube and an x-ray film cassette and pivoting this unit about a pivot axis lying in the desired layer. In this case, sharp images are produced on the x-ray film only of the details of the selected layer, whereas the remaining details are imaged in a blurry fashion. It is disadvantageous here that the secondary radiation grid, which must be aligned to the focus of the x-ray tube, on account of the necessary movement of the radiographic unit comprised of the x-ray tube and the x-ray film cassette, can exhibit only lamellae or leaves which extend in the direction of movement. There consequently results only incomplete stray radiation suppression.